Automatically release I/O permissions on shutdown

Get_io_perms() is renamed to rget_io_perms() and automatically registers
a function to release I/O permissions on shutdown.

Actually release I/O permissions on Solaris and iopl()-supporting
operating systems like Linux.

This patch fixes quite a few programmers which forgot to release I/O
permissions on shutdown, and it simplifies the shutdown and error
handling code for all others.

Do not call exit(1) if I/O permissions are denied and return an error
instead. This part of the patch was written by Niklas Söderlund.

Corresponding to flashrom svn r1551.

Signed-off-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net>
Signed-off-by: Niklas Söderlund <niso@kth.se>
Acked-by: Michael Karcher <flashrom@mkarcher.dialup.fu-berlin.de>
diff --git a/gfxnvidia.c b/gfxnvidia.c
index ddf82e7..782d692 100644
--- a/gfxnvidia.c
+++ b/gfxnvidia.c
@@ -84,7 +84,6 @@
 	 * by PCI restore.
 	 */
 	pci_cleanup(pacc);
-	release_io_perms();
 	return 0;
 }
 
@@ -92,7 +91,8 @@
 {
 	uint32_t reg32;
 
-	get_io_perms();
+	if (rget_io_perms())
+		return 1;
 
 	io_base_addr = pcidev_init(PCI_BASE_ADDRESS_0, gfx_nvidia);